The Sherlock team does know how to tease its fans.

During the recently held San Diego Comic Con, the stars of the show took the time to post a snap on twitter bearing signs with three keywords that will give the fans an idea what to expect for Season 4.

The words on the signs were, Thatcher, Smith and Sherrinford.

According to Games Radar, the clue about Thatcher refers to a possible reunion of Adler and Holmes. The report hinted that Thatcher could refer to a case called "The Six Thatchers" which earlier appeared in the show's second season. This was the same episode where Sherlock lost Irene Adler to execution so this clue could hint at a reunion between the two.

Sadly for fans of the show, there is a strong possibility that Season 4 could be the show's last.

In an interview, showrunner Steven Moffat acknowledged that while they may want to keep the show going for a long time, it grows exceedingly difficult with both of the show's stars Benedict Cumberbatch and Martin Freeman getting more Hollywood projects.

Both men have been cast as part of the Marvel Cinematic Universe, on top of other projects in the years since Season 3.

"I don't know how long we can keep it going. I'm personally willing but I'm hardly the main draw. I would be moderately surprised if this was the last time we ever made this show," Moffat said.

Cumberbatch, in a separate interview also expressed uncertainty over the fate of the show.

"It's been great fun to come back and do it. How it will continue in the future, who knows? It's not just about what any of us want. "It's about what's actually right for the show, to be honest, and that has to be judged very carefully. Painful thing to say, but maybe Series 4 is it. Who knows?" he said to Collider.